The present disclosure relates to treatment of subterranean formations and, in specific examples, to altering the permeability of the near wellbore region of a subterranean formation such that a treatment fluid may be uniformly applied to the near wellbore region in consolidation treatments.
In soft formations or formations that may have little or no natural cementation, sand and other fines, collectively referred to herein as “unwanted solids,” may be produced along with the hydrocarbons. Unwanted solid production can plug wells, erode equipment, and reduce well productivity. Failure to successfully control unwanted solids may lead to loss of profitable production or even the abandonment of the project. In certain producing regions, solids control completions are the dominant type and result in considerable added expense to operations. Over the life of such wells, the ratio of unwanted solids to hydrocarbons recovered may be undesirable in view of the cost of producing the unwanted solids, separating them from the hydrocarbons, and disposing of them, which may result in a significant economic loss.
A variety of techniques have been used to control unwanted solids. One method of solids control is to produce fluids from the formation at flow rates low enough to not affect the stability of sand bridges and other sand formations. However, instability and collapse of sand formations may still occur due to pressure cycling or unintentional error in setting production rates. Another technique for controlling solids comprises placing a gravel pack to provide a physical barrier to solids movement. Gravel packs, however, may be difficult to install and expensive. Further, it may be difficult to determine an appropriate screen size and gravel packs may also be subject to screen erosion and screen plugging. Sometimes chemical treatments, referred to herein as “consolidation treatments” are used. Consolidation treatments typically involve chemically binding the unwanted solids particles that make up the formation matrix while simultaneously maintaining sufficient permeability to ensure desirable production rates. However, formation permeabilities may vary and the treatment fluids used in the consolidation treatment may selectively enter the zones in the near wellbore region of the subterranean formation with the highest permeabilities. Unwanted solids in zones with low permeability may then escape treatment and remain a problem during production. Further, lack of uniform treatment may waste treatment fluids and increase downtime, consequently increasing operational expenses.